Abstract: The phytochemistry and antimicrobial effects of water, methanol, chloroform and petroleum ether extracts of Senna alata leaves were studied. Extracts tested at a final concentration of 500 μg mL produced in vitro antimicrobial activities in assays against clinical isolates of Staphylococus aureus, Candida albicans, Escherichia coli, Proteus vulgaris, Pseudomonans aeruginosa and Bacillus subtilis. The zones of inhibitions produced by the extracts in agar diffusion assay against the test micro organisms ranged from 8 to 20 mm while the gentamycin antibiotic control produced zones that measured 5 mm. Preliminary phytochemical analysis of the plant extracts showed the presence of phenols, tannins, anthraquinoes, saponins, flavonoids.